The present invention relates to a novel lubricating fluid which may supersede a lubricating oil used for a machine and a device or a hydraulic oil used for a cylinder, or the like.
A lubricating oil is sent into a rotation part or a slide part of a machine or a device by a pump and the like, and prevents a sliding part from being burnt while reducing resistance caused by a rotation and a slide. In ordinary cases, when a machine or a device, for example, a machine tool such as a lathe, a milling cutter or a machining center or the like, is used for cutting or grinding a workpiece, a cutting oil or the like is flowed down over the part to be machined for various purposes. The spread cutting oil splashes on a bearing and a slide part of a bed, which results in mixing the lubricating oil and the cutting oil. Therefore, lubricating oils are retrieved as part of cutting oils and recycled while the lubricating oils are newly refilled.
Since waste oil problems are raised when these oils are disposed, and a volatile and transpiratory gas emitted from the cutting oils has the risk of impairing the health of workers as well as deterioration of working environment, water-base cutting fluids are expected and various kinds of water-base cutting fluids have been proposed. However, when a water-base cutting fluid is used, for example, in a machine tool, the lubricating oil used in the machine tool flowing into the cutting fluid makes an oil film appear on the surface of the cutting fluid and leads to the solidification of the lubricating oil. Consequently, the machine itself has the risk of being adversely affected because the cutting fluid is circulated in the machine. Further, when the cutting fluid is disposed, it is necessary to separate the lubricating oil from the cutting fluid. The task is difficult, so that it has cost higher than one using a cutting oil.
The use of a water-base lubricating fluid with a corresponding water-base cutting fluid, therefore, causes no problems, even if the lubricating fluid has been mixed with the cutting fluid. In addition, any problems, such as separation of oil and water, or the like are not raised when the waste liquid is disposed. However, there have been no water-base lubricating fluids, because when a water-base lubricating fluid is used in a machine tool such as an expensive machining center and the like, there are not only problems with rust, but also the risk that a lot of resistance may be applied onto a high-speed rotating driving part and a heavily loaded base part in the process of cutting, which leads to the risk of seizure.
Furthermore, hydraulic oils used for operating devices, such as cylinders, or the like are conventionally oily. Describing this by exemplifying a cylinder used for a bulldozer, or the like, for example, it is important not only to operate a piston by supplying oil for a cylinder, but also to prevent the cylinder from seizure, even when a heavy load is applied. For this reason, there has been no choice but to use oil-base hydraulic oils. Although water is used as a hydraulic fluid in the field of press working and the like, there have not been such types that are used by circulating a hydraulic fluid between the press and the tank.
The object of the present invention is to provide a water-base lubricating fluid or a hydraulic fluid in place of an oil-base fluid which has been used as a lubricating oil or a hydraulic oil applied onto the operating portion of a machine and a device.
As the result of repeated studies to develop an excellent lubricating fluid having high lubricating effects without any problems with its waste fluid disposal, the inventors of the present invention have attained the present invention.
It is the main point of a lubricating fluid according to the present invention to comprise fluoride ion; hydrogencarbonate ion; and water-soluble alcohols or their derivatives. The term xe2x80x9clubricating fluidxe2x80x9d as used herein means a hydraulic fluid and the like used for operating a driving device such as a cylinder, or the like as well as a lubricating fluid used for lubricating a sliding part of a machine element.
In such lubricating fluid, the above-mentioned water-soluble alcohols or their derivatives may be glycerin or ethylene glycol.
Such lubricating fluid further contains a rust inhibitor.
The embodiment of a lubricating fluid according to the present invention will now be described in detail. First, the lubricating fluid according to the present invention comprises fluoride ion; hydrogencarbonate ion; and water-soluble alcohols or their derivatives.
The essential components contained in the lubricating fluid of the present invention are fluoride ion; hydrogencarbonate ion; and water-soluble alcohols or their derivatives. The concentration of fluoride ion and hydrogencarbonate ion is not particularly limited, but the lubricating fluid preferably contains within the range of 1xc3x9710xe2x88x923 to 10% by weight of fluoride ion, and within the range of 1xc3x9710xe2x88x922 to 10% by weight of hydrogencarbonate ion. Of the water-soluble alcohols or their derivatives, glycerin, ethyl alcohol, methyl alcohol, and ethylene glycol or their derivatives, or the like are preferable. Among them, glycerin or ethylene glycol or its derivative is particularly preferable. The concentration of glycerin and ethylene glycol or its derivative included in the lubricating fluid is not particularly limited, but it is preferably within the range of 1 to 70% by weight, more preferably within the range of 2 to 60% by weight.
Accordingly, the lubricating fluid of the present invention can be prepared by dissolving, for example, a predetermined amount of sodium bicarbonate, sodium fluoride, and ethylene glycol in distilled water and service water or mineral water or the like, but the manner is not limited. Sodium ion may particularly be substituted by one of other alkali metal ions or other cations.
The lubricating fluid of the present invention may be used alone, but it may further include other additives. A typical example of other additives is a rust inhibitor. It is, however, not limited to a rust inhibitor, but a suitable amount of thickener, leveling agent, colorant, and perfume may be added to the lubricating fluid in accordance with the actual service condition within the scope of keeping its performance.
The rust inhibitor used in the present invention may be any of rust inhibitors available in the market. For example, an ion coating rust inhibitor, a rust inhibitor including such as paraffin wax, carnauba wax, and the like, and a non-amine rust inhibitor, or the like are preferably used. The rust inhibitor is added as necessary in some applications to the lubricating fluid described in this patent application.
The lubricating fluid of the present invention can be obtained by mixing and/or dissolving fluoride ion, hydrogencarbonate ion, water-soluble alcohols or their derivatives, and other arbitrary components into water or other water-soluble solvent within the scope of the appropriate concentration.
The present invention relates to a lubricating fluid including the above-mentioned composition, wherein the surface of a steel product or the like is protected by coating the product by fluoride ion, hydrogencarbonate ion and/or a water-soluble alcohol, moreover, the sliding resistance between members of the product is reduced by lowering the friction factor. As a result, when the members are slid each other, there is no possibility of their contact surfaces seizing, even if the pressure applied onto the surfaces between both members gets higher due to heavy load.
Further, for example, when the lubricating fluid is used in a machine tool as the water-base cutting fluid, the lubricating fluid and the cutting fluid are not separated, even if they have been mixed because this lubricating fluid is water-base. Especially, the lubricating fluid of the present invention has no risk of river contamination caused by special liquid waste disposal because it comprises of inorganic components existing in nature.
The lubricating fluid according to the present invention may also be used on any place where either of an axial load or a thrust load is applied. Consequently, the lubricating fluid can be used not only as a lubricating fluid for a wide variety of machine tools, but also as a lubricating fluid in sequential feeding system using a pump or the like.
Furthermore, the lubricating fluid according to the present invention can be used as a hydraulic fluid in place of a conventional hydraulic oil or hydraulic water for an oil hydraulic cylinder and a hydraulic cylinder. Particularly, the lubricating fluid of the present invention is the most suited to be used as a hydraulic fluid for a cylinder on which a heavy load is applied, such as a power shovel or a bulldozer, because the lubricating fluid reduces frictional resistance. It is needless to say that the lubricating fluid can be used as a hydraulic fluid for a hydraulic equipment.
The present invention will now be described in more detail by showing the following examples. The present invention is, however, not limited to these examples. The invention can be embodied by adding a variety of improvements, modifications, and changes, based on knowledges of those skilled in the art within a scope that does not depart from the essentials of the invention.